Dementia is an increasing global issue, currently affecting an estimated 50 million people worldwide. This number is predicted to increase to 82 million by the year 2030, due to the ageing global population. Theoretically, preventing late-onset dementia may seem extremely difficult as the greatest risk factor, age, is unmodifiable. However, it is estimated that a third of dementia cases could potentially be prevented or delayed by removing or reducing modifiable risk factors. Increasing evidence suggests that chronic stress, which may arise from experiencing a traumatic event or daily stress, may be a potential risk factor for dementia. Whilst it may not play a vital role in causing the syndrome, stress may contribute to the progression of cognitive decline, which is the main symptom of dementia. The primary stress hormone, cortisol, may have detrimental effects on cognitive brain regions when its levels are elevated for long durations. Preliminary evidence suggests that stress may have different effects on brain structure and function, depending on the individual’s age when exposed to the stress. Stress during early and later life may lead to more permanent brain changes, which may contribute to cognitive decline in later life. Limited evidence links chronic stress or major trauma at specific stages of the lifespan, with cognitive decline and incidence of dementia. Whether or not an accumulation of stress across the lifespan influences later life cognition and risk of dementia, still remains to be determined. Understanding to what extent stressful events are risk factors for later-life cognitive decline and dementia will be crucial to the implementation of targeted psychosocial interventions efforts.